The present invention relates to a novel micropattern polarized element of a high polarizability and the production method thereof, and further to a liquid crystal display device capable of stereoscopic vision using micropattern polarized elements each having a different polarized light axis.
Hitherto, various polarized elements wherein plural polarized regions each having a different polarized light transmitting direction are formed as patterns are known.
For example, Japanese Patent Laid-Open No. 96905/1987 proposed a method of, after coating a resist on a stretched polyvinyl alcohol film, applying a pattern exposure and development to pattern the resist, and dyeing the portions of the stretched polyvinyl alcohol film not covered by the resist with a dichroic compound to form a polarized region of a desired pattern.
Sadeg M. Faris reports, in Society of Information and Display Conference, a method of, after coating a resist in pattern on a stretched dichroic polyvinyl alcohol film, dissolving off with aqueous sodium hydroxide solution to form a patterned polarized film, and preparing a polarized element called xcexcPol by laminating two such patterned polarized films of which the polarizing axes are crossed at right angle to use for stereoscopic vision (SID 91 DIGEST, pages 840-843).
Japanese Patent Laid-Open No. 261024/1995 proposes a method of irradiating a thin film of a photo-orienting substance coated on a substrate with polarized light in a pattern form and forming thereon a solution of a dichroic dye followed by orienting to form a polarized region of a desired pattern.
Japanese Patent Laid-Open No. 73015/1997 provides a micropatterned polarized element formed by covering a substrate with an oriented film of a fluorine resin, and after coating thereon a resin followed by patterning, accumulating thereon a material containing a dichroic dye.
Japanese Patent Laid-Open No. 160932/1998 proposes a polarized element obtained by sticking plural polarized pieces on a substrate such a manner that the polarized light transmitting axes of the adjacent polarized pieces are different from each other.
Japanese Patent Laid-Open No. 160933/1998 proposes a polarized element having plural polarized light transmitting axes obtained by forming an oblong or lattice-form partially polarized member the polarized light transmitting axis of which is directed to one direction by partially scraping the polarized film disposed on a substrate by a dicer, placing thereon a polarized film having the polarization axis in a different direction, and scraping off the polarized film portions on the existing polarized member by a dicer, or a polarized element sticking each other the partially polarized members scraped by the dicer, each having a different polarized light transmitting axis.
On the other hand, in regard to a stereoscopic vision, various methods are proposed and a binocular disparty stereoscopic vision utilizing the polarization is one of the methods. This system is also called a polarized spectacles system and is the system that spectacles using polarized plates the polarized light axes of which cross at right angle each other are put on the right eye and the left eye and the images for the right eye and the left eye having a binocular parallax are observed by dividing the image information for the left and the image information of the right between the left eye and the right eye respectively by the polarized plates of the spectacles of the observer. In the system, projecting images each having a different polarization axis, a method of synthesizing the images formed using two display apparatus or two projecting apparatus by a half mirror or a polarization mirror is employed. In this case, the display apparatus become expensive and the system is suitable in the case of showing stereoscopic images for many observers but has the problem that the system is unsuitable to for office use, a display, etc., for domestic use or for seeing by few peoples.
Thus, it has been proposed that by using micropattern polarized elements the polarized light axes of which cross at right angle in a same plane for a display apparatus, it is possible to simultaneously display the image of a right eye and the image for a left eye in one display apparatus and further the apparatus can be produced at a low cost.
The polarized elements of forming patters of plural polarized regions each having the different polarized light transmission direction, which has hitherto been known, have the following problems.
In the method of Japanese Patent Laid-Open No. 96905/1987, because a stretched PVA film is dyed, not only the polarization performance is lowered as compared with an ordinary method of stretching after drying but also there is a problem that in the case of forming a pattern by developing, the stretched PVA film is swelled to spoil the uniaxial property, and the polarization performance is more lowered, whereby a polarized element having a satisfactory polarizability is not obtained.
In the method (SID SI DIGEST, pages 840-843, U.S. Pat. No. 5,327,285) reported by Sadeg M. Faris in Society of Information and Display Conference, there are-problems that because after coating a resist on a stretched dichroic polyvinyl alcohol film followed by patterning, in the case of dissolving off with an aqueous sodium hydroxide solution, the remaining polarized element portions are swelled, whereby the polarization performance is lowered, and also because the polarized element is produced by sticking two kinds of substrates, the polarization axes cross at right angle, each other, a very high position matching precision is required at sticking.
In the method of Japanese Patent Laid-Open No. 261024/1995, a thin film of a photo-orienting substance coated on a substrate is irradiated with a polarized light in a pattern form and solution of a dichroic dye is coated thereon and oriented, but in regard to the method, Ichimura reported as follows in Mol. Cryst. Liq. Cryst., 1997, Vol. 298, pp. 221-226. That is, when the oriented dye film is observed by an interatomic force microscope (AFM), the portions that the dye is uniformly oriented as shown in FIG. 1(a) (in the Ichimura""s report, and so forth) and the portions (crater) that dye scarcely exist and is not oriented as shown in FIG. 1(b) are observed. The absorbances of the portion of FIG. 1(a) and the portion of FIG. 1(b) are measured by a microscopic spectrophotometer and it has been seen that because of the many craters, the uniformity of the whole dye film is lowered and the polarization performance becomes insufficient. When the present inventors calculated the dichroic ratio (DR) from the portion of FIG. 1(a) and the portion of FIG. 1(b), there is a large difference such as DR(a)≅30 and DR(b)≅1.3, and in a wide area including them, DR=5 to 6, which is not a level which could be satisfied as a display element. In addition, the calculation of the dichroic ratio (DR) is carried out by the following formula
DR=A∥/Axe2x8axa5
A∥: Absorbance when the polarization axis is parallel to the molecular long axis of the oriented dye.
Axe2x8axa5: Absorbance when the polarization axis is perpendicular to the molecular long axis of the oriented dye.
In the method of Japanese Patent Laid-Open No. 73015/1997, after covering a substrate with the oriented film of a fluorine resin and coating thereon a resist followed by pattering, a material containing a dichroic dye is accumulated to form a micropatterned polarized element but there is a problem that in the case of treating the oriented film of a fluorine resin with a resist, because the orienting property of the fluorine resin oriented film is perhaps reduced by the influence of the resist film remaining as the thin film thereof on the surface or the influence of the development treatment, the orienting property of the material containing the dichroic dye accumulated thereon is not sufficient and also the polarization performance is insufficient.
In the method of Japanese Patent Laid-Open No. 160932/1998, the polarized element is formed by sticking plural polarized pieces to a substrate such that the polarized light transmitting axes of the adjacent polarized pieces differ but there is a problem that in the case of sticking plural polarized pieces, a very high position-matching precision is required.
In the method of Japanese Patent Laid-Open No. 160933/1998, a polarized element having plural polarized light transmitting axes obtained by forming an oblong or lattice-form partially polarized member the polarized light transmitting axis of which is directed to one direction by partially scraping the polarized film disposed on a substrate by a dicer, placing thereon a polarized film having the polarization axis in a different direction, and scraping off the polarized film portions on the existing polarized member by a dicer, or a polarized element sticking each other the partially polarized members scraped by the dicer, each having a different polarized light transmitting axis is formed but there are problems that a very high precision is required in the step of scraping off by a dicer and also in the case of sticking plural partially polarized members each having a different polarized light transmitting axis, a very high position-matching precision is required.
In view of the above-described circumstances, as the result of various investigations for providing a micropattern polarized element excellent in the partial orientation of a dichroic dye compound without need of a very high position-matching precision as the above-described sticking method of prior art and also for providing a production method of the micropattern polarized element, the inventors have accomplished the present invention.
The present invention relates to a polarized element which is in a practical usable level as a display element by reducing as low as possible the occurrences of the portions of scarcely existing a dye and is not oriented, which becomes the problem in the method of Japanese Patent Laid-Open No. 261024/1995 and wholly increasing the orientation of a dichroic compound.
The present inventors made various investigations about a photoactive molecular layer more suitable to a micropattern-form anisotropic sequence of a dichroic dye molecule and have discovered that a liquid crystalline polycondensated high molecule such as polyamide, polyimide, polyester, etc.; a liquid crystalline polyaddition reaction high molecule such as polyurethane, etc,; or liquid crystalline polyvinyl cinnamate; each bonded with a photoactive group has excellent characteristics. In the invention, it has astonishingly found that when a liquid crystalline high molecular thin film having a photoactive group is used as an oriented film, the craters as shown in FIG. 1(b) are very less and if any, the size of the craters is far small. Thus, it has been seen that the average dichroic ratio becomes particularly large and the polarized element which can be sufficiently practically used as a display element can be produced.
That is, the present invention is as follows. The 1st aspect of the invention is a polarized element having a liquid crystalline resin thin film layer having a photoactive group on a substrate and a layer containing a dichroic molecule in contact with the liquid crystalline resin thin film layer, wherein the dichroic molecule is arranged in a micropattern form.
The 2nd aspect of the invention is the polarized element of the aspect 1 wherein the photoactive group is a group containing at least one double bond selected from non-aromatic Nxe2x95x90N, non-aromatic Cxe2x95x90C, and non-aromatic Cxe2x95x90N.
The 3rd aspect of the invention is the polarized element of the aspect 1 or 2 wherein the liquid crystalline resin thin film is the thin film of polyamide, polyimide, polyester, or a polyurethane resin.
The 4th aspect of the invention is the polarized element of the aspect 1 or 2 wherein the liquid crystalline resin thin film is a polyvinyl cinnamate resin thin film.
The 5th aspect of the invention is the polarized element of the aspect 1 to 4 wherein the dichroic molecule is a dye having a lyotropic liquid crystalline property.
The 6th aspect of the invention is the polarized element of the aspect 5 wherein the dye having a lyotropic liquid crystalline property is a dye having a hydrophilic substituent.
The 7th aspect of the invention is the polarized element of the aspect 6 wherein the hydrophilic substituent is a sulfonic group, a carboxylic group, an amino group, or a hydroxyl group.
The 8th aspect of the invention is a method of producing a polarized element by forming the thin film of a liquid crystalline resin having a photoactive group on a substrate, and after irradiating the thin film with a linear polarized light, arranging a dichroic molecule on the thin film in a micropattern form.
The 9th aspect of the invention is the method of producing a polarized element of the aspect 8 wherein the irradiation of the linear polarized light is carried out through a micropattern-form mask.
The 10th aspect of the invention is the method of producing a polarized element of the aspect 8 wherein the irradiation of the linear polarized light is carried out using a laser light having a polarizing property.
The 11th aspect of the invention is a method of producing a polarized element by forming the thin film of a liquid crystalline resin having a photoactive group on a substrate, irradiating the thin film with a linear polarized light through a micropattern-form mask, and then after irradiating with a linear polarized light having a different polarized light axis through a different micropattern-form mask, arranging a dichroic molecule on the thin film in a micropattern form.
The 12th aspect of the invention is a stereoscopic display apparatus which is a liquid display apparatus having upper and lower substrates facing each other, wherein at least one of the substrate is a substrate having the polarized element of the aspect 1 to 7.
A liquid crystalline high molecule is a high molecule showing a liquid crystalline property under a certain condition, and as such a liquid crystalline high molecule, there are known a high molecule showing a so-called lyotropic liquid crystalline property in the existence of a solvent and a thermotropic liquid crystalline high molecule showing a liquid crystalline structure in a molten state without the existence of a solvent. In general, the liquid crystalline high molecule has a layer wherein the chain of the molecule is highly oriented in the fluid direction in the liquid crystal state and by fixing the oriented state, a high strength.high elastic material is obtained. Furthermore, many investigations of obtaining an oriented film of a low molecular nematic liquid crystal by utilizing the high orienting property of the liquid crystalline high molecule thin film are made recently.
In the present invention, the object of the liquid crystalline high molecule having the photoactive group is not to obtain a high strength material but is to utilize that the highly orienting property of the high molecular thin film can sufficiently control the orientation of a dichroic molecular layer having the lyotropic liquid crystalline property formed thereon.